Design and construction of embedded steel-plate cell breakwater

The South breakwater in the North harbor of the port of Wakayama Shimotsu is the first breakwater in Japan constructed using the embedded steel plate cell method. The embedded steel plate cell method is executed by first inserting steel plate cells shaped like cylinders and made by welding steel plates into the seabed, then filling the interiors of the steel plate cells with sand or rock material to form the wall body, but it had never been used to build a breakwater and a design method had not been established. So in order to adopt the embedded steel plate cell method, hydraulic model testing was done to clarify the hydraulic properties of the breakwater and acting wave force and development was conducted to incorporate a design method that evaluates the decline of the strength of the ground in which the cells are embedded under repeated wave load into an actual design for the first time. This report describes the hydraulic properties of the breakwater based on the hydraulic model test results. Next it describes the design method established for repeated wave load. It concludes with an introduction to the state of execution of the breakwater.